Imaging optical system

ABSTRACT

An imaging optical system for a projection exposure system has at least one anamorphically imaging optical element. This allows a complete illumination of an image field in a first direction with a large object-side numerical aperture in this direction, without the extent of the reticle to be imaged having to be enlarged and without a reduction in the throughput of the projection exposure system occurring.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of, and claims priority under35 USC §120 to, international application PCT/EP2011/065823, filed Sep.13, 2011, which claims benefit under 35 USC §119 of German ApplicationNo. DE 10 2010 040 811.5, filed Sep. 15, 2010 and also claims priorityunder 35 USC §119(e) to U.S.S.N. 61/383,079, filed Sep. 15, 2010. Thedisclosure of each of these applications is incorporated herein byreference in its entirety.

FIELD

The disclosure relates to an imaging optical system for a projectionexposure system, an illumination optical system for a projectionexposure system and an optical system with an imaging optical system ofthis type. The disclosure also relates to a projection exposure systemwith an optical system of this type, a reticle for a projection exposuresystem, a method for producing a microstructured component with the aidof this projection exposure system and a component produced by themethod.

BACKGROUND

Imaging optical systems are known from DE 10 2007 062 198 A1, U.S. Pat.No. 7,414,781 B2, U.S. Pat. No. 7,682,031 B2 and from WO 2010/091800 A1.Lithography systems are also known from US 2008/0036986 A1.

SUMMARY

The disclosure provides an imaging optical system for a projectionexposure system with improved imaging quality.

According to the disclosure, it was recognised that with an increase inthe object-side numerical aperture, the object-side main beam angle hasto be enlarged, which can lead to shading effects owing to the absorberstructure and to problems with the layer transmission, in particular tostrong apodisation effects owing to the reticle coating.

According to the disclosure, it was further recognised that a reticle ofa predetermined size can be imaged from an object field with apredetermined imaging scale on a predetermined illumination field via ananamorphic imaging optical system, in particular via an anamorphicimaging projection lens system, by which the illumination field iscompletely illuminated in the direction of the first imaging scale,while a reduced imaging scale in a second direction does not have anegative effect on the throughput of the projection exposure system, butcan be compensated by suitable measures.

An anamorphic lens system therefore allows both complete illumination ofan image face with a large object-side numerical aperture in the firstdirection (without the extent of the reticle to be imaged having to beenlarged in this first direction and without a reduction in thethroughput of the projection exposure system occurring) and theminimisation of losses in imaging quality caused by inclined incidenceof the illumination light.

An image flip is avoided by sign-identical imaging scales in thedirection of the two principal planes. The optical system, in particularin the direction of the two principal planes, has positive imagingscales.

In one aspect, the disclosure provides an imaging optical system for aprojection exposure system which includes at least one anamorphicallyimaging projection lens system having sign-identical imaging scales inthe direction of the two principal planes.

In some embodiments, the at least one anamorphically imaging projectionlens system has at least two part lens systems, of which at least oneimages anamorphically. Such an imaging optical system is particularlyfavourable to construct and allows particularly flexible adaptation ofthe imaging properties to the respective desired properties. Inparticular the first, i.e. object-side part lens system, imagesanamorphically. This can ensure that the radiations incident on theobject field and reflected thereby do not overlap. The second part lenssystem is also anamorphic. It can also be non-anamorphic.

The projection lens system can have a circular exit pupil. Theimage-side numerical aperture is therefore direction-independent. Thisensures an orientation-independent resolution. The anamorphic lenssystem according to the disclosure therefore has, in particular, anentry pupil with an elliptical shape. The semi-axes of the ellipsetherefore have the same or rather the reverse relationship to oneanother as the different imaging scales or the different object-sidenumerical apertures.

The anamorphically imaging projection lens system can include at leastone mirror. A smaller number of mirrors lead here to smallertransmission losses. A larger number of mirrors allows a more flexibleand improved correction of imaging errors and allows a higher numericalaperture. According to the disclosure, the projection lens systemincludes at least one mirror, such as at least four mirrors, at leastsix mirrors, at least eight mirrors. The mirrors may, in particular, beconfigured as EUV radiation-reflecting mirrors.

An optical element with a freeform face allows a particularly flexibledesign of the imaging properties. This opens up, in particular with agiven number of mirrors of the imaging optical system, further degreesof freedom for correcting imaging errors.

The imaging scale in a first direction can be at least one and a halftimes as large as in a second direction. It is, in particular, at leasttwice as large as in the second direction. Imaging scale is taken tomean here and below the absolute amount of the imaging scale given bythe ratio of the imaging size to the article size, i.e. the size of thestructure to be imaged in the image field of the projection lens systemto the size of the structure to be imaged in the object field. It isensured as a result that an illumination field with a predeterminedwidth with a predetermined reticle, in particular with a reticle of apredetermined size can be exposed perpendicular to the scanningdirection over the complete width. A smaller imaging scale, i.e. astronger reduction, in the direction perpendicular to the width of theillumination field can be otherwise compensated, in particular by anincreased scanning speed and therefore has no disadvantageous effects.

The reduced imaging scale in the direction perpendicular to the scanningdirection, in particular, does not lead to throughput losses.

Direction-dependent different object-side numerical apertures can allowan advantageous design of the imaging optical system. In particular,problems with shading effects and layer transmission on the reticle canbe avoided by this. The object-side numerical aperture (NAO) in aspecific direction is, in particular, at least one and a half times aslarge, in particular at least twice as large, as in a directionperpendicular to this.

The illumination system preferably has an exit pupil, the shape of whichis configured corresponding to the entry pupil of the projection lenssystem. According to the disclosure, an illumination system with anelliptical exit pupil is therefore provided.

This is, in particular, achieved by an elliptical pupil facet mirror orby an elliptical arrangement of the pupil facets on the pupil facetmirror, i.e. an arrangement, in which the envelope of all pupil facetsforms an ellipse.

The semi-axes of the elliptically configured pupil facet mirror or theexit pupil of the illumination system have, in particular, the samerelationship to one another as the two different imaging scales of theprojection lens system or the semi-axes of the entry pupil thereof.

An imaging optical system with a large image-side numerical aperture, asmall main beam angle and large image-side scanning slot width allowsparticularly good projection of the structures of a reticle in the imagefield.

In one aspect, the disclosure provides an illumination optical systemfor a projection exposure system. The illumination optical systemincludes at least one pupil facet mirror. The illumination system has anelliptical exit pupil, the semi-axis lengths of which differ from oneanother by at least 10%. Such a system is particularly well adapted toan anamorphically imaging projection lens system. With an ellipticalconfiguration of the pupil facet mirror, an elliptical exit pupil of theillumination optical system can be particularly easily achieved.

The advantages of an optical system including an illumination opticalsystem disclosed herein, as well as the advantages a projection exposuresystem including an illumination optical system as disclosed herein,correspond to those noted above with respect to the illumination opticalsystem.

In some embodiments, a projection exposure system includes a reticleholder which can be displaced in a scanning direction to hold a reticle,wherein the imaging scale of the imaging optical system in a scanningdirection is smaller than perpendicular thereto. For such a projectionexposure system, the throughput loss in the scanning direction can becompensated completely by a higher scanning speed.

In some embodiments an illumination optical system has an ellipticalpupil facet mirror and an elliptical exit pupil. The semi-axis lengthsof the elliptical exit pupil differ from one another by at least 10%,and the semi-axis lengths of the elliptical pupil facet differ from oneanother by at least 10%. The imaging scale of such an imaging optical inthe scanning direction is, in particular, at most half as great asperpendicular thereto. The ratio of the imaging scales in the scanningdirection and perpendicular to this is, in particular, 1:2, 1:3, 1:4,1:5, 1:6, 1:8, 1:10, 2:3, 2:5 or 3:4. The radiation source may be an EUV(Extreme Ultraviolet) light source, for example an LPP (Laser ProducedPlasma) light source or a GDP (Gas Discharge Produced Plasma) lightsource.

A reticle, in which the critical dimension in the scanning directiondiffers from that perpendicular thereto, is particularly well suited foruse with an anamorphically imaging projection optical system. Both thestructures to be imaged on the reticle and the total size thereof arepreferably configured in accordance with the different imaging scales inthe scanning direction or perpendicular to this. In order to take intoaccount the greater reduction, the reticle is configured correspondinglylarger, in particular in the scanning direction.

The advantages of a production method and a component made using such amethod correspond to those which have already been described above withreference to the projection exposure system according to the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and details of the disclosure emerge from thedescription of a plurality of embodiments with the aid of the drawings,in which:

FIG. 1 schematically shows a meridional section through a projectionexposure system for EUV lithography;

FIG. 2 schematically shows a cutout of the projection exposure systemaccording to FIG. 1 to illustrate the beam path in the imaging opticalsystem according to a first embodiment;

FIG. 3 shows a view in accordance with FIG. 2 in a plane perpendicularthereto;

FIGS. 4 and 5 show views according to FIGS. 2 and 3 of a furtherembodiment;

FIGS. 6 and 7 show corresponding views of a third embodiment; and

FIGS. 8 and 9 show corresponding views of a fourth embodiment.

DETAILED DESCRIPTION

FIG. 1 schematically shows, in a meridional section, the components of aprojection exposure system 1 for microlithography. An illuminationsystem 2 of the projection exposure system 1, apart from a radiationsource 3, includes an illumination optical system 4 for exposing anobject field 5 in an object plane 6. A reticle 7, which is arranged inthe object field 5 and is held by a reticle holder 8, only showncutout-wise, is exposed here.

A projection optical system 9 indicated only schematically in FIG. 1 isused to image the object field 5 in an image field 10 in an image plane11. The projection optical system 9 is therefore also designated animaging optical system. A structure on the reticle 7 is imaged on alight-sensitive layer of a wafer 12 which is arranged in the region ofthe image field 10 in the image plane 11 and is held by a wafer holder13 also shown schematically.

The radiation source 3 is an EUV radiation source which emits EUVradiation 14. The wavelength of the emitted useful radiation of the EUVradiation source 3 is in the range from 5 nm to 30 nm. Otherwavelengths, which are used in lithography, and are available forsuitable light sources, are also possible. The radiation source 3 may bea plasma source, for example a DPP source or an LPP source. A radiationsource based on a synchrotron can also be used as the radiation source3. Information on a radiation source of this type can be found by theperson skilled in the art, for example, in U.S. Pat. No. 6,859,515 B2. Acollector 15 is provided to bundle the EUV radiation 14 from the EUVradiation source 3.

The EUV radiation 14 is also designated illumination light or imaginglight.

The illumination optical system 4 includes a field facet mirror 16 witha large number of field facets 17. The field facet mirror 16 is arrangedin a plane of the illumination optical system 4, which is opticallyconjugated to the object plane 6. The EUV radiation 14 is reflected bythe field facet mirror 16 to a pupil facet mirror 18 of the illuminationoptical system 4. The pupil facet mirror 18 has a large number of pupilfacets 19. The field facets 17 of the field facet mirror 16 are imagedin the object field 5 with the aid of the pupil facet mirror 18.

For each field facet 17 on the field facet mirror 16, there is preciselyone associated pupil facet 19 on the pupil facet mirror 18. Between afield facet 17 and a pupil facet 19, in each case, a light channel isconfigured. The facets 17, 19 of at least one of the facet mirrors 16,18 may be switchable. For this purpose, a microelectromechanical system(MEMS) may be provided. The facets 17, 19 may, in particular, betiltably arranged on the facet mirror 16, 18. It is possible here toonly configure a part, for example at most 30%, at most 50% or at most70% of the facets 17, 19 to be tiltable. It may also be provided thatall the facets 17, 19 are tiltable. The switchable facets 17, 19 are, inparticular, the field facets 17. By a tilting of the field facets 17,the allocation thereof to the respective pupil facets 19 and thereforethe configuration of the light channels can be varied. For furtherdetails of the facet mirrors 16, 18 with tiltable facets 17, 19 andfurther details of the illumination optical system 4, reference is madeto DE 10 2008 009 600 A1.

The illumination optical system 4 may also have further mirrors 20, 21and 22, which form a transmission optical system 23. The last mirror 22of the transmission optical system 23 is a grazing incidence mirror. Thepupil facet mirror 18 and the transmission optical system 23 form afollowing optical system for transferring the illumination light 14 intothe object field 5. The transmission optical system 23 can be dispensedwith, in particular, when the pupil facet mirror 18 is arranged in anentry pupil of the projection optical system 9.

The illumination optical system 4 has an exit pupil with a shape adaptedto (e.g., corresponding to) the shape of an entry pupil of theprojection optical system 9. The exit pupil of the illumination opticalsystem 4 is, in particular, elliptical. This can be achieved, inparticular, by an elliptically configured pupil facet mirror 18. As analternative to this, the pupil facets 19 can also be arranged on thepupil facet mirror 18 in such a way that they have an ellipticallyconfigured envelope.

The semi-axes of the elliptical pupil facet mirror 18 have, inparticular, two different semi-axis lengths, the greater semi-axislength in particular being at least one and a half times as great, inparticular at least twice as great, as the first semi-axis length. Thesemi-axis lengths are, in particular, in the ratio 1:2, 1:3, 1:4, 1:5,1:6, 1:8, 1:10, 2:3, 2:5 or 3:4.

The semi-axes of the exit pupil of the illumination optical system 4therefore have two different semi-axis lengths, the greater semi-axislength in particular being at least one and a half times as great, inparticular at least twice as great, as the first semi-axis length. Thesemi-axis lengths are, in particular in the ratio 1:2, 1:3, 1:4, 1:5,1:6, 1:8, 1:10, 2:3, 2:5 or 3:4.

For a simpler description of positional relationships, a Cartesianxyz-coordinate system is drawn in the figures, in each case. The x-axisin FIG. 1 runs perpendicular to the plane of the drawing and into it.The y-axis runs to the right. The z-axis runs downward. The object plane6 and the image plane 11 both run parallel to the xy-plane.

The reticle holder 8 can be displaced in a controlled manner so that inthe projection exposure system, the reticle 7 can be displaced in adisplacement direction in the object plane 6. Accordingly, the waferholder 13 can be displaced in a controlled manner so that the wafer 12can be displaced in a displacement direction in the image plane 11. As aresult, the reticle 7 can be scanned through the object field 5, and thewafer 12 can be scanned through the image field 10. The displacementdirection in the figures is parallel to the y-direction. It will also bedesignated the scanning direction below. The displacement of the reticle7 and the wafer 12 in the scanning direction can preferably take placesynchronously with respect to one another.

FIGS. 2 and 3 show the optical design of a first configuration of theprojection optical system 9. The beam path of individual beams of theradiation 14 extending from a central object field point and from tworespective object field points defining the two opposing edges of theobject field 5 are shown. The projection optical system 9 according toFIGS. 2 and 3 has a total of six mirrors, which are numberedconsecutively M1 to M6 proceeding from the object field 5 in thedirection of the beam path. The reflection faces of the mirrors M1 to M6calculated in the design of the projection optical system 9 are shown inthe figures. Only one section of the faces shown is partially actuallyused for the reflection of the radiation 14, as can be seen from thefigures. The actual configuration of the mirrors M1 to M6, in otherwords, may be smaller than shown in the figures (the actualconfiguration may include only part of the calculated reflection faceshown in the figures).

A pupil face 24 is located between the mirror M2 and the mirror M3. Thepupil face 24 is not necessarily flat. It may be curved. Moreover, anintermediate image face 25 is located between the mirror M4 and themirror M5. The intermediate image face 25 is not necessarily flat. Itmay be curved. The mirrors M1 to M4 therefore form a first part lenssystem 26. The mirrors M5 and M6 form a second part lens system 27.

The first part lens system 26 is an anamorphic lens, i.e. it imagesanamorphically. The second part lens system 27 is also an anamorphiclens, i.e. it images anamorphically. It is likewise possible, however,for the second part lens system 27 to be configured to benon-anamorphic.

At least one of the mirrors M1 to M6 is configured to be ananamorphically imaging optical element. The projection optical system 9includes, in particular, at least one anamorphically imaging mirror,such as at least two anamorphically imaging mirrors, at least threeanamorphically imaging mirrors, at least four anamorphically imagingmirrors, at least five anamorphically imaging mirrors, at least sixanamorphically imaging mirrors, at least seven anamorphically imagingmirrors, at least eight anamorphically imaging mirrors.

The projection optical system 9 therefore has, in a first direction, afirst imaging scale and, in a second direction, a second imaging scalewhich is different from this. The second imaging scale is, inparticular, at least one and a half times as great, in particular atleast twice as great, as the first imaging scale.

The projection optical system 9 is, in particular, configured so thatthe amount of the imaging scale in the scanning direction is smallerthan the amount of the imaging scale in a direction perpendicular to thescanning direction. The amount of the imaging scale in the scanningdirection is, in particular, at most three quarters as great (e.g., atmost two thirds as great, at most half as great) as the imaging scale ina direction perpendicular to the scanning direction.

The projection optical system 9 has a direction-dependant object-sidenumerical aperture (NAO), i.e. the entry pupil deviates from thecircular shape. The object-side numerical aperture (NAO) in a specificdirection, namely in the direction of the large imaging scale, is inparticular at least one and a half times as large (e.g., at least twiceas large) as in a direction perpendicular thereto.

The mirror M6 has a through-opening 28 for radiation 14 to pass through.Located between the mirrors M5 and M6 is a further pupil face 29. Thepupil face 29 is not necessarily flat. It may be curved.

The mirrors M1 to M6 are configured to reflect EUV radiation. Theycarry, in particular, multiple reflection layers for optimising theirreflection for the impinging EUV illumination light 14. The reflectioncan be all the better optimised, the closer the impingement angle of theindividual beams on the mirror surfaces to the perpendicular incidence.

The mirrors M1 to M5 have reflection faces, which are closed, in otherwords without a through-opening.

The mirrors M1, M4 and M6 have concave reflection faces. The mirrors M2,M3 and M5 have convex reflection faces.

The mirrors M1 to M6 of the projection optical system 9 are configuredas freeform faces that cannot be described by a rotationally symmetricalfunction. Other configurations of the projection optical system 9 arealso possible, in which at least one of the mirrors M1 to M6 has afreeform reflection face of this type. A freeform face of this type maybe produced from a rotationally symmetrical reference face. Freeformfaces of this type for reflection faces of the mirrors of projectionoptical systems of projection exposure systems for microlithography areknown from US 2007-0058269 A1.

The freeform face can be mathematically described by the followingequation:

${Z\left( {x,y} \right)} = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {\sum\limits_{j = 2}^{N}{\frac{C_{j}}{N_{radius}^{m + n}}x^{m}y^{n}}}}$

wherein there applies:

$j = {\frac{\left( {m + n} \right)^{2} + m + {3n}}{2} + 1}$

Z is the arrow height of the freeform face at the point x, y, whereinxX²+y²=r².

c is a constant, which corresponds to the summit of the curve of acorresponding asphere. k corresponds to a conical constant of acorresponding asphere. C_(j) are the coefficients of the monomialsx^(m)y^(n). Typically, the values of c, k and C_(j) are determined onthe basis of the desired optical properties of the mirror within theprojection optical system 9. N_(radius) is a standardisation factor forthe coefficients C_(j). The order of the monomial, m+n, can be varied asdesired. A higher order monomial can lead to a design of the projectionoptical system with better image error correction, but is, however, morecomplex to calculate. m+n can adopt values between 3 and more than 20.

Freeform faces can be mathematically described by Zernike polynomials,which, for example, are described in the manual of the optical designprogram CODE V®. Alternatively, freeform faces can be described with theaid of two-dimensional spline surfaces. Examples of this are Beziercurves or non-uniform rational basis splines (NURBS). Two-dimensionalspline surfaces may, for example, be described by a network of points inan xy-plane and associated z-values or by these points and gradientspertaining to them. Depending on the respective type of spline surface,the complete surface is obtained by interpolation between the networkpoints using, for example, polynomials or functions, which have specificproperties with regard to their continuity and differentiability.Examples of this are analytical functions.

Optical design data of the projection optical system 9 will besummarised below in tables, the data having been obtained with the aidof the optical design program Code V®.

The first of the following tables gives for the optical surfaces of theoptical components and for the aperture stop, in each case, thereciprocal value of the summit of the curve (radius) and a thickness,which corresponds to the z-spacing of adjacent elements in the beampath, proceeding from the image plane 11, in other words counter to thelight direction. The second table gives the coefficients C_(j) of themonomials x^(m)y^(n) in the freeform face equation given above for themirrors M1 to M6.

In a further table, the amount in mm is also given, along which therespective mirror, proceeding from a mirror reference design wasdecentred (Y-decentre) and rotated (X-rotation). This corresponds to aparallel displacement and a tilting in the freeform face design method.The displacement takes place in the y-direction here and the titling isabout the x-axis. The angle of rotation is given here in degrees.

Surface Radius Thickness Operating mode image plane INFINITE 852.884 M6−889.919 −802.884 REFL M5 −219.761 1800.787 REFL M4 −999.946 −434.619REFL M3 −1033.356 483.832 REFL M2 2464.083 −947.116 REFL M1 1323.6881047.116 REFL object plane INFINITE 0.000

Coefficient M6 M5 M4 K 3.303831E−03 2.041437E−02 −1.056546E−01  Y0.000000E+00 0.000000E+00 0.000000E+00 X2 1.106645E+00 4.620513E+001.065419E+00 Y2 1.316656E+00 4.632819E+00 2.089523E+00 X2Y−6.987016E−02  6.244905E−02 2.322141E−01 Y3 −1.544816E−01 −2.303227E−01  −2.158981E−01  X4 3.297744E−02 9.371547E−02 7.579352E−02X2Y2 6.476911E−02 1.671737E−01 8.744751E−02 Y4 5.431530E−02 7.743085E−022.360575E−01 X4Y −7.040479E−04  4.607809E−03 3.961681E−03 X2Y3−6.159827E−03  −1.034287E−02  9.782459E−03 Y5 −4.061987E−03 −3.840440E−03  −1.297054E−01  X6 1.398226E−03 3.085471E−03 6.847894E−03X4Y2 2.977799E−03 8.906352E−03 6.372742E−03 X2Y4 4.433992E−038.678073E−03 −2.569810E−02  Y6 1.255594E−03 1.683572E−03 9.106731E−02X6Y 2.969767E−04 1.881484E−04 1.342374E−03 X4Y3 −2.820109E−04 −1.123168E−03  −5.896992E−03  X2Y5 −3.654895E−04  −5.949903E−04 1.660704E−03 Y7 8.966891E−05 −3.952323E−04  −3.764049E−02  Nradius2.899772E+02 6.300046E+01 2.064580E+02 Coefficient M3 M2 M1 K5.744686E−01 −3.325393E+02 −1.583030E−02 Y 0.000000E+00  0.000000E+00 0.000000E+00 X2 3.551408E−01  3.277030E−01 −2.811984E−02 Y22.123536E+00  1.609563E+00 −4.135835E−01 X2Y 2.013521E−01 −6.948142E−01−3.866470E−02 Y3 −1.210907E−02   3.694447E−01 −1.853273E−02 X45.478320E−02  1.369729E−01  1.349339E−03 X2Y2 7.482002E−02  1.984843E−01 3.032808E−03 Y4 8.327949E−02 −1.227576E−01 −2.824781 E−03  X4Y−2.048831E−03  −4.568931E−02 −4.300195E−04 X2Y3 −4.029059E−03 −1.713508E−02 −6.501645E−04 Y5 −1.415756E−02   6.185385E−03 3.144628E−03 X6 1.998416E−04 −1.834856E−02  6.906841E−05 X4Y2−1.979383E−03  −3.309794E−02  5.274081E−05 X2Y4 −5.943296E−03 −5.169942E−02 −1.330272E−03 Y6 1.246118E−03 −1.603819E−01 −1.363317E−02X6Y 1.584327E−04  7.876367E−03 −2.377257E−05 X4Y3 −3.187207E−04 −1.244804E−02 −2.251271E−04 X2Y5 −5.566691E−04  −5.746055E−02−9.996573E−04 Y7 −1.399787E−03  −3.870909E−02  4.001012E−03 Nradius8.132829E+01  7.472082E+01  1.311311E+02

Image Coefficient M6 M5 M4 M3 M2 M1 plane Y-decentre −51.252 −99.408123.654 215.631 528.818 512.855 0.000 X-rotation 0.323 7.067 −2.44410.483 16.940 3.488 0.000

The projection optical system 9, in the y-direction, i.e. in thescanning direction, has an imaging scale of 1:8, i.e., the reticle 7 inthe object field 5, in the scanning direction, is eight times as greatas its image in the image field 10. The projection optical system 9, inthe x-direction, i.e. perpendicular to the scanning direction, has animaging scale of 1:4. The projection optical system 9 is thereforereducing. An image-side numerical aperture of the projection opticalsystem 9 is 0.5. The image-side numerical aperture of the projectionoptical system 9 is, in particular, at least 0.4. The image field 10 hasa size of 2 mm×26 mm, wherein the 2 mm is in the scanning direction andthe 26 mm is perpendicular to the scanning direction. In particular inthe scanning direction, the image field 10 may also have a differentsize. The size of the image field 10 is at least 1 mm×10 mm.Perpendicular to the scanning direction, the image field 10, inparticular, has a width of more than 13 mm. The image field 10 is, inparticular, rectangular. The projection optical system 9, in particular,has an image-side scanning slot width of at least 13 mm, in particularmore than 13 mm, in particular at least 26 mm. The projection opticalsystem 9 has an object-side main beam angle for the field centre pointof 6°. The object-side main beam angle for the field centre point is, inparticular at most 7°. It has an optical overall length of 2000 mm.

The object field 5 in this embodiment has a size of 16 mm×104 mm. Inthis case, the 16 mm is in the scanning direction and the 104 mm isperpendicular to the scanning direction.

The reticle 7 is also adapted to the different imaging scales in thescanning direction and perpendicular thereto. It has structures withdifferent minimal structure sizes in the scanning direction and in thedirection perpendicular thereto. The structures on the reticle 7 mayhave, in the scanning direction and in the direction perpendicular tothis, in particular, dimensions, which are, in each case, an integralmultiple of these minimal structure sizes. The ratio of the minimalstructure sizes in the scanning direction and perpendicular to this isprecisely inversely proportional to the ratio of the imaging scales inthese directions. The minimal structure sizes in the scanning directionand perpendicular to this differ, in particular, by at least 10%, inparticular at least 20%, in particular at least 50% from one another.

The reticle 7 has a width in the direction perpendicular to the scanningdirection of at least 104 mm. The reticle 7, in particular, has a lengthadapted to the stronger reduction in the scanning direction. The reticle7 has, in particular, a width of 104 mm and a length of 264 mm. Thelength of the reticle is, in particular, greater than 132 mm. It is, inparticular, at least 140 mm, in particular at least 165 mm, inparticular at least 198 mm.

A further configuration of the projection optical system 9, which can beused in the projection exposure system 1, is shown in FIGS. 4 and 5.Components which correspond to those which have already been describedabove with reference to FIGS. 2 and 3 have the same reference numeralsand will not be discussed again in detail.

The mirror M3 has no through-opening in the optically used region.However, the mechanical configuration of the mirror M3 may be selectedsuch that the light, which runs from the mirror M4 to the mirror M5,passes through a mirror opening of the monolithically configured mirrorbody of M3.

The mirrors M1, M3, M4 and M6 have concave reflection faces. The mirrorsM2 and M5 have convex reflection faces.

In this embodiment, the beam path between the mirrors M2 and M3intersects with the beam path between the mirrors M4 and M5.

In this embodiment, the mirror M5, relative to the image field 10 in thescanning direction, is arranged on the same side as the object field 5.

The optical design data of the projection optical system 9 according toFIGS. 4 and 5 will in turn be summarised in tables below. Themathematical description of the freeform faces corresponds to that whichhas already been described above with reference to the configurationsaccording to FIGS. 2 and 3. The structure of the tables with respect tothe configuration according to FIGS. 4 and 5 also corresponds to thatwith respect to the configuration according to FIGS. 2 and 3.

Surface Radius Thickness Operating mode image plane INFINITE 689.272 M6−731.552 −639.272 REFL M5 −241.671 1420.179 REFL M4 −1500.000 −580.907REFL M3 1422.356 1010.728 REFL M2 661.083 −1110.728 REFL M1 1384.3111210.728 REFL object plane INFINITE 0.000

Coefficient M6 M5 M4 K 0.000000E+00 0.000000E+00 0.000000E+00 Y0.000000E+00 0.000000E+00 0.000000E+00 X2 1.697113E+00 4.496118E+001.030719E+01 Y2 1.683950E+00 4.083378E+00 1.147196E+01 X2Y 1.755515E−01−3.170399E−01  −1.434807E+00  Y3 2.279761E−02 9.028788E−02 1.085004E+00X4 5.443962E−02 4.335109E−02 2.308628E−01 X2Y2 1.503579E−01 8.531612E−027.598943E−01 Y4 5.203904E−02 6.130679E−02 2.980202E−01 X4Y 5.039890E−03−1.771794E−02  −8.711086E−03  X2Y3 8.907227E−03 −1.404665E−02 8.302498E−04 Y5 5.015844E−03 8.045746E−03 4.101109E−02 Nradius2.899772E+02 6.300046E+01 2.064580E+02 Coefficient M3 M2 M1 K0.000000E+00 0.000000E+00  0.000000E+00 Y 0.000000E+00 0.000000E+00 0.000000E+00 X2 −4.645076E−01  −5.243755E−01  −3.303400E−01 Y2−2.057326E−01  −2.274245E−02  −7.527525E−01 X2Y −3.583366E−02 1.523089E+00 −2.593623E−03 Y3 3.371920E−02 −2.167244E+00  −3.182409E−02X4 9.534050E−05 7.127442E−02 −8.002659E−04 X2Y2 4.301563E−03−3.064519E−01  −5.376311E−03 Y4 −9.145920E−04  7.458445E−01−7.154305E−03 X4Y 9.453851E−05 1.770844E−01 −2.938545E−04 X2Y3−2.757417E−04  2.079536E−01  2.101675E−03 Y5 4.683904E−05 −1.544216E−01  6.098608E−04 Nradius 8.132829E+01 7.472082E+01  1.311311E+02

Image Coefficient M6 M5 M4 M3 M2 M1 plane Y-decentre 0.000 99.374−121.476 −185.579 311.769 482.388 0.000 X-rotation −4.418 −8.837 −1.27116.249 8.734 −1.361 0.000

FIGS. 6 and 7 show a further design of the projection optical system 9,which can be used in the projection exposure system 1. Components whichcorrespond to those which have already been described above withreference to FIGS. 2 and 3 have the same reference numerals will not bediscussed again in detail.

The projection optical system 9 according to FIGS. 6 and 7 has a totalof six mirrors M1 to M6, which are numbered consecutively M1 to M6 inthe direction of the beam path proceeding from the object field 5. Theprojection optical system 9 according to FIGS. 6 and 7 has an opticaloverall length of 1865 mm.

The mirrors M1, M4 and M6 have a concave reflection face. The mirror M5has a convex reflection face. The mirrors M2 and M3 are convex in onedirection and concave in the orthogonal direction with respect thereto,in other words have the form of a saddle face in the centre point of themirror.

The mirror M5 is also arranged in this embodiment, in the scanningdirection with respect to the image field 10, on the same side as theobject field 5.

The optical design data of the projection optical system 9 according toFIGS. 6 and 7 will in turn be shown in tables below. The mathematicaldescription of the freeform faces corresponds to that which was alreadydescribed above with reference to the configuration according to FIGS. 2and 3. The structure of the tables with respect to the configurationaccording to FIGS. 6 and 7 also corresponds to that with respect to theconfiguration according to FIGS. 2 and 3.

Surface Radius Thickness Operating mode image plane INFINITE 752.663 M6−770.716 −702.663 REFL M5 −150.912 1382.613 REFL M4 −996.191 −579.950REFL M3 −3722.693 805.250 REFL M2 −19143.068 −805.250 REFL M1 1526.6261011.848 REFL object plane INFINITE 0.000

Coefficient M6 M5 M4 K 0.000000E+00 0.000000E+00 0.000000E+00 Y0.000000E+00 0.000000E+00 0.000000E+00 X2 1.014388E+00 5.967807E+001.640439E+00 Y2 9.176806E−01 5.297172E+00 1.185698E+01 X2Y 2.666213E−02−2.932506E−02  −5.795084E−01  Y3 1.276213E−02 −1.747940E−01 2.665088E−01 X4 3.194237E−02 1.741906E−01 4.142971E−02 X2Y2 5.891573E−024.136465E−01 −2.431409E−02  Y4 2.892148E−02 1.408837E−01 8.604418E−01X4Y 5.053354E−04 8.947414E−03 1.339774E−03 X2Y3 3.013407E−034.414092E−02 −2.210148E−02  Y5 2.088577E−03 3.281648E−02 −1.242199E+00 Nradius 2.899772E+02 6.300046E+01 2.064580E+02 Coefficient M3 M2 M1 K0.000000E+00  0.000000E+00 0.000000E+00 Y 0.000000E+00  0.000000E+000.000000E+00 X2 −3.018727E+00  −4.089101E−01 −1.333076E−01  Y22.571222E+00  3.746969E+00 8.408741E−01 X2Y −2.111739E−01  −1.877269E−013.355099E−02 Y3 −1.035192E−03  −1.810657E−01 −3.518765E−03  X4−9.587021E−05  −1.882449E−03 2.861048E−03 X2Y2 −2.154549E−02  8.492037E−02 3.127905E−02 Y4 1.331548E−02 −4.386749E−01 7.200871E−03X4Y 3.718201E−03 −6.344503E−03 −2.655046E−04  X2Y3 4.305507E−03−1.265202E−01 −6.358900E−03  Y5 −5.587835E−03  −6.311675E−01−1.276179E−02  Nradius 8.132829E+01  7.472082E+01 1.311311E+02

Image Coefficient M6 M5 M4 M3 M2 M1 plane Y-decentre −11.861 78.940−76.134 224.849 34.161 393.420 0.000 X-rotation −4.070 −6.401 −16.914−20.375 −18.683 −9.044 0.000

FIGS. 8 and 9 show a further configuration of a projection opticalsystem 9, which can be used in the projection exposure system 1.Components which correspond to those which have already been describedabove with reference to FIGS. 2 and 3 have the same reference numeralsand will not be discussed again in detail.

The projection optical system 9 according to FIGS. 8 and 9 has eightmirrors M1 to M8. The mirrors M1 to M6 form the first part lens system26. The mirrors M7 and M8 form the second part lens system 27. Themirror M8, within the optical useful region, has the through-opening 28for imaging light to pass through. The mirrors M1 to M7 have reflectionfaces, which are closed, in other words without a through-opening withinthe optical useful region. The projection optical system 9 according toFIGS. 8 and 9 therefore has precisely one mirror with a through-opening28 within the optical useful region. Obviously, it is also possible toconfigure a projection optical system 9 with eight mirrors M1 to M8, ofwhich more than one has a through-opening within the optical usefulregion.

The pupil face 24 is located in the beam path between the mirrors M3 andM5. The pupil face 29 is located between the mirrors M7 and M8. Theprojection optical system 9 according to FIGS. 8 and 9 also has two partlens systems 26, 27. It produces precisely one intermediate image, whichlies geometrically in the region of the through-opening of the mirrorM8.

The mirrors M1, M2, M6 and M8 have a concave reflection face. The mirrorM7 has a convex reflection face.

The projection optical system according to FIGS. 8 and 9 has animage-side numerical aperture of 0.65. The optical design data of theprojection optical system 9 according to FIGS. 8 and 9 are summarisedbelow in tables as in the preceding examples.

Surface Radius Thickness Operating mode image plane INFINITE 845.498 M8−876.024 −795.498 REFL M7 −180.463 1850.000 REFL M6 −1124.587 −954.502REFL M5 −488.461 539.347 REFL M4 −385.935 −268.946 REFL M3 −899.608563.864 REFL M2 −1862.135 −962.532 REFL M1 −5181.887 1182.769 REFLobject plane INFINITE 0.000

Coefficient M8 M7 M6 M5 K 0.000000E+00 0.000000E+00 0.000000E+000.000000E+00 Y 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 X23.488069E+00 1.173931E+01 2.308119E+01 1.973785E+01 Y2 2.635738E+001.010579E+01 9.438034E+00 5.768532E+00 X2Y −3.059528E−01  −2.733318E−01 −2.266607E+00  −2.615013E+00  Y3 4.818868E−03 6.423471E−01 4.511519E−013.223897E+00 X4 1.179868E−01 5.618198E−01 1.276169E+00 3.423570E−01 X2Y23.744431E−01 9.722072E−01 1.994073E+00 1.253707E+00 Y4 1.874806E−015.624878E−01 9.258956E−01 1.143661E+00 X4Y 4.142568E−03 7.747318E−03−2.207925E−01  2.696457E−02 X2Y3 −2.457062E−02  2.657340E−02−4.677376E−02  1.053608E−01 Y5 −1.021381E−02  −2.031996E−02 3.450492E−01 1.716687E+00 X6 1.995975E−02 5.531407E−02 1.199126E−011.472679E−02 X4Y2 4.538384E−02 1.603998E−01 2.637967E−01 4.745154E−02X2Y4 5.093101E−02 1.653739E−01 3.269947E−01 4.959237E−01 Y6 1.573648E−026.733509E−02 −1.107783E−01  −1.594589E+00  X6Y −4.813461E−03 1.089425E−03 −8.010947E−02  −1.168696E−04  X4Y3 −6.317680E−03 −3.797390E−03  −4.398398E−03  1.681727E−02 X2Y5 −4.665516E−03 −6.378254E−03  1.634222E−02 −8.741752E−01  Y7 −1.452902E−03 1.323361E−03 −8.378471E−01  −2.083305E−01  X8 2.243101E−03 8.933777E−03−9.452801E−03  8.039655E−04 X6Y2 1.043837E−02 3.095089E−02 9.332196E−025.834641E−03 X4Y4 1.610588E−02 4.686597E−02 1.032458E−01 −1.262475E−01 X2Y6 1.112924E−02 3.372176E−02 −1.634446E−01  −2.791598E−01  Y82.847098E−03 9.333073E−03 −6.596064E−01  3.828685E−01 X8Y 0.000000E+000.000000E+00 0.000000E+00 0.000000E+00 X6Y3 0.000000E+00 0.000000E+000.000000E+00 0.000000E+00 X4Y5 0.000000E+00 0.000000E+00 0.000000E+000.000000E+00 X2Y7 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 Y90.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 X10 0.000000E+000.000000E+00 0.000000E+00 0.000000E+00 X8Y2 0.000000E+00 0.000000E+000.000000E+00 0.000000E+00 X6Y4 0.000000E+00 0.000000E+00 0.000000E+000.000000E+00 X4Y6 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00X2Y8 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 Y100.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 Nradius 4.270420E+028.460702E+01 3.587547E+02 1.359154E+02 Coefficient M4 M3 M2 M1 K0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 Y 0.000000E+000.000000E+00 0.000000E+00 0.000000E+00 X2 7.762408E+00 0.000000E+000.000000E+00 2.415351E+01 Y2 5.991623E+00 2.100665E+01 1.742497E+012.450758E+01 X2Y −9.407982E−01  −1.845560E+01  0.000000E+00 2.857360E+00Y3 7.990315E−02 1.826735E+00 0.000000E+00 −8.203766E−01  X4 2.084759E−010.000000E+00 0.000000E+00 −1.195250E−01  X2Y2 2.343824E−01 0.000000E+000.000000E+00 9.400506E−02 Y4 6.849174E−02 0.000000E+00 0.000000E+001.027239E−01 X4Y −3.590847E−02  0.000000E+00 0.000000E+00 5.178501E−02X2Y3 −1.676285E−02  0.000000E+00 0.000000E+00 5.698284E−02 Y51.244977E−03 0.000000E+00 0.000000E+00 2.110062E−01 X6 7.609826E−040.000000E+00 0.000000E+00 1.852743E−03 X4Y2 1.642005E−02 0.000000E+000.000000E+00 −5.347458E−02  X2Y4 6.253616E−03 0.000000E+00 0.000000E+00−2.587706E−01  Y6 1.353703E−03 0.000000E+00 0.000000E+00 1.608009E−01X6Y −2.568254E−03  0.000000E+00 0.000000E+00 5.587846E−04 X4Y3−4.755388E−03  0.000000E+00 0.000000E+00 5.397733E−02 X2Y5−6.793506E−04  0.000000E+00 0.000000E+00 −2.400347E−01  Y7−1.374859E−05  0.000000E+00 0.000000E+00 2.641466E−01 X8 2.488086E−040.000000E+00 0.000000E+00 5.593305E−04 X6Y2 1.255585E−03 0.000000E+000.000000E+00 6.244473E−03 X4Y4 1.194473E−03 0.000000E+00 0.000000E+001.145315E−01 X2Y6 3.001214E−04 0.000000E+00 0.000000E+00 8.712058E−02 Y85.813757E−05 0.000000E+00 0.000000E+00 6.570255E−01 X8Y 0.000000E+000.000000E+00 0.000000E+00 0.000000E+00 X6Y3 0.000000E+00 0.000000E+000.000000E+00 0.000000E+00 X4Y5 0.000000E+00 0.000000E+00 0.000000E+000.000000E+00 X2Y7 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 Y90.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 X10 0.000000E+000.000000E+00 0.000000E+00 0.000000E+00 X8Y2 0.000000E+00 0.000000E+000.000000E+00 0.000000E+00 X6Y4 0.000000E+00 0.000000E+00 0.000000E+000.000000E+00 X4Y6 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00X2Y8 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 Y100.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 Nradius 7.497396E+012.029987E+02 2.738127E+02 2.966746E+02

Coefficient M8 M7 M6 M5 M4 Y-decentre 0.000 −116.456 154.238 192.354412.808 X-rotation 4.164 8.327 3.019 9.973 −2.768 Coefficient M3 M2 M1Image plane Y-decentre 554.416 783.491 867.803 0.000 X-rotation −2.8298.552 0.503 0.000

As can be seen from the preceding description of the embodiments, theprojection optical system 9 is configured in such a way that it has anintermediate image in the two principal planes.

As can also be seen from the previous description of the embodiments,the imaging scales of the projection optical system 9, in particular ofthe two part lens systems 26, 27, in the direction of the two principalplanes, in each case have the same sign. In particular, they both have apositive sign. Therefore no image flip occurs.

To produce a microstructured or nanostructured component, the projectionexposure system 1 is used as follows: firstly, the reticle 7 and thewafer 12 are provided. A structure on the reticle 7 is then projectedonto a light-sensitive layer of the wafer 12 with the aid of theprojection exposure system 1. By developing the light-sensitive layer, amicrostructure or nanostructure is then produced on the wafer 12 andtherefore the microstructured component, for example a semiconductorcomponent in the form of a highly integrated circuit, is produced.

During the exposure of the light-sensitive layer on the wafer 12, thelatter is displaced with the aid of the wafer holder 13 in the scanningdirection. In this case, the displacement takes place, in particular,synchronously with respect to a displacement of the reticle 7 with theaid of the reticle holder 8 in the scanning direction. The reducedimaging scale of the projection optical system 9 in the scanningdirection can be compensated by a higher scanning speed.

1.-20. (canceled)
 21. An imaging optical system, comprising: ananamorphically imaging projection lens system comprising at least fourmirrors, wherein: the anamorphically imaging projection lens system hasa first imaging scale in a first direction and a second imaging scale ina second direction orthogonal to the first direction; a ratio of thesecond imaging scale to the first imaging scale is at least 4:3; theimaging optical system is a microlithographic imaging optical system;and the imaging optical system has an image-side numerical aperture ofat least 0.4.
 22. The imaging optical system of claim 21, wherein theanamorphically imaging projection lens system comprises first and secondpart lens systems, and the first part lens system images anamorphically.23. The imaging optical system of claim 21, wherein the anamorphicallyimaging projection lens system has a circular exit pupil.
 24. Theimaging optical system of claim 21, wherein the anamorphically imagingprojection lens system comprises at least one mirror having a freeformface.
 25. The imaging optical system of claim 21, wherein the imagingoptical system has a direction-dependent object-side numerical aperture.26. The imaging optical system of claim 21, wherein imaging opticalsystem has: an object-side main beam angle for the field centre point ofless than 7° ; and an image field having a width of more than 13 mm in adirection perpendicular to a scanning direction of the imaging opticalsystem.
 27. An optical system, comprising: an imaging optical system ofclaim 21; and an illumination optical system configured to transferradiation from a radiation source to an object field of the imagingoptical system.
 28. The optical system of claim 27, wherein theillumination optical system comprises a pupil facet mirror, theillumination optical system has an elliptical exit pupil with semi-axislengths which differ from one another by at least 10%, and theillumination optical system is microlithographic illumination opticalsystem.
 29. A projection exposure system, comprising: a radiation sourceconfigured to produce radiation; and an optical system, comprising: animaging optical system of claim 21; and an illumination optical systemconfigured to transfer the radiation from the radiation source to anobject field of the imaging optical system.
 30. The projection exposuresystem of claim 29, wherein the illumination optical system comprises apupil facet mirror, the illumination optical system has an ellipticalexit pupil with semi-axis lengths which differ from one another by atleast 10%, and the illumination optical system is a microlithographicillumination optical system.
 31. The projection exposure system of claim29, further comprising a reticle holder which is displaceable in ascanning direction, wherein an imaging scale of the imaging opticalsystem is smaller in the scanning direction than in a directionperpendicular to the scanning direction.
 32. The projection exposuresystem of claim 31, further comprising a reticle having a width of atleast 104 mm and a length of more than 132 mm.
 33. A method, comprising:providing a projection exposure system, comprising: a radiation sourceconfigured to produce radiation; and an optical system, comprising: animaging optical system of claim 21; and an illumination optical system;using the illumination optical system to illumination a reticle in anobject plane of the imaging optical system; and using the imagingoptical system to project a structure of the reticle onto aradiation-sensitive material.
 34. The method of claim 33, wherein theillumination optical system comprises a pupil facet mirror, theillumination optical system has an elliptical exit pupil with semi-axislengths which differ from one another by at least 10%, and theillumination optical system is a microlithographic illumination opticalsystem.
 35. An imaging optical system, comprising: an anamorphicallyimaging projection lens system having a first imaging scale in a firstdirection, a second imaging scale in a second direction orthogonal tothe first direction, the first imaging scale being different from thesecond imaging scale, wherein the anamorphically imaging projection lenssystem has an elliptical entry pupil and a circular exit pupil, and theimaging optical system is a microlithographic imaging optical system.36. The imaging optical system of claim 35, wherein during use of theanamorphically imaging optical system, for each field point of an objectfield of the anamorphically imaging optical system, an incoming beam ofillumination radiation has no overlap with a reflected beam ofradiation.
 37. The imaging optical system of claim 36, wherein the ratioof the second imaging scale to the first imaging scale is at least 4:3.38. An optical system, comprising: the imaging system of claim 35; andan illumination optical system configured to transfer radiation from aradiation source to an object field of the imaging optical system,wherein an elliptical exit pupil of the illumination optical systemcorresponds to the elliptical entry pupil of the anamorphically imagingprojection lens system.
 39. The optical system of claim 38, whereinsemi-axes of the elliptical exit pupil of the illumination opticalsystem have a ratio which is inverse to the imaging scales of theanamorphically imaging projection lens system in correspondingdirections.
 40. A projection exposure system, comprising: a radiationsource configured to produce radiation; and an optical system,comprising: an imaging optical system of claim 35; and an illuminationoptical system configured to transfer the radiation from the radiationsource to an object field of the imaging optical system.
 41. A method,comprising: providing a projection exposure system, comprising: aradiation source configured to produce radiation; and an optical system,comprising: an imaging optical system of claim 35; and an illuminationoptical system; using the illumination optical system to illumination areticle in an object plane of the imaging optical system; and using theimaging optical system to project a structure of the reticle onto aradiation-sensitive material.